Re: No Till for sandy soil?
Barry Garcia wrote:
>
> I've been following this no-till thread with interest, and i'm wondering,
> what can it do for soil that is almost pure sand? Drainage of course is no
> problem, but what benefits could it add?
>
> The reason I ask is I've been digging up the side yard in preparation for
> making it a tropical style side garden (It can get quite warm there, it
> felt like it was about 70 degrees in that spot when the wind was calm).
> It's not a big space, maybe 20 by 8 feet. I would like to place my banana
> plants (the Rajapuri and my new M. acuminata "Sumatrana"), as well as some
> gingers and a few ferns, and whatever else I can fit there and have a nice
> lush spot to relax in.
Barry
Making a good soil out of sand is in my opinion is actually more
difficult problem than dealing with clay, but once again (as with clay)
I get the impression just mixing humus manually with the soil is not
very efficient at improving it.
Apart from the disadvantage of its over-free drainage, sand is not very
flush with food. For one thing, being very largely quartz, an oxide of
silica, it has little to offer itself in the way of useful nutrients.
Furthermore, there is very little humus in it. As humus is the material
which retains both nutrients and moisture in the root zone, plants
growing in sand tend to be hungry and in dry times very thirsty as well.
The most successful efforts at improvement probaby come from what might
perhaps be regarded as an adaptation of the raised bed, constructed not
on the soil surface but in a hollowed-out area. I have never had the
opportunity to try it myself, but from what I can make out one starts by
scooping out a bed at least 4" deep, heaping up the excavated sand as a
low wall around it to help direct any applied moisture in the way it
should go.. This hollow is then filled to the surface with whatever
suitable humus-forming materials one can get, as well as some good
quality loam or loamy clay to provide both some minerals and "body", and
also what ever compost can be spared, all covered with a surface layer
of organic mulch (regularly renewed as necessary). As sands are
notoriously light in their content of useful minerals, a long-term
supplement of mineral powders to supply such dietary necessities as
slow-release phosphate and potassium, plus a yearly dressing of kelp
powder (or some seaweed in your organic layers) to ensure a good kit of
trace minerals and you should be in business.
Note the 4" would be a minimum depth for the bed. if you can get
sufficient materials to fill it, up, twice as deep would give an even
better start. Whatever materials are used in the bed construction,
finished compost will be the most useful if applied just below the
surface, protected by just a light covering mulch to prevent it drying
out and putting its contained organisms in danger. I have never myself
grown bananas and have no idea what sort of roots they have. Perhaps it
would be worth making deeper subsiduary hollows just where they are to
go and so giving them a bit more working depth. However, I have no doubt
that if you CAN manage around 8" to start with the combination of
natural downward penetration of the organic matter and the action of the
burrowing roots themselves will quite quickly produce whatever depth of
improved soil they need to flourish.
The theory is that, provided you keep up the supply of humus by regular
mulching your good growing soil will not be permanently confined to the
original hollow, but will gradually involve a building up of the deeper
layers as well and this will almost certainly include an improvement in
their water-holding capacity as well as their nutrient content.
Moira-
Tony & Moira Ryan <theryans@xtra.co.nz>
Wainuiomata, New Zealand. (on the "Ring of Fire" in the SW Pacific).
Lat. 41:16S Long. 174:58E. Climate: Mediterranean/Temperate
